MBB 142 lec Drosophila Flashcards
The best understood of all developmental model systems
Drosophila
Drosophila hatches from the egg as a/an?
Larva
Two axes which define early Drosophila body patterning
Antero-posterior and Dorso-ventral axes
The four regions that the dorso-ventral axis of Drosophila is divided into (from ventral to dorsal)
Mesoderm, Neuroectoderm/ Ventral ectoderm, Dorsal ectoderm, Amnioserosa
What is the amnioserosa?
An extraembryonic membrane that is sloughed off during development
The region/s that the ventral ectoderm will develop into
Ventral epidermis and Neural tissue
The region/s that the dorsal ectoderm will develop into
Epithelium
The regions that the antero-posterior axis will develop into (3)
Head, Thorax, and Abdomen
Number of parasegments
14
Number of thoracic and abdominal segments
3 and 8
Distinguishing characteristics of the segments (2)
Denticles and Bristles
Specialized structure at the posterior end of the larva
Telson
Specialized structure at the anterior end of the larva
Acron
Process of change from larva to adult
Metamorphosis
Group of cells set aside in the embryo that eventually give rise to adult structures, such as the wings and legs
Imaginal discs
Does the antero-posterior axis finish developing first before development of the dorso-ventral axis begins?
No, they occur simultaneously
The early multinucleate stage in Drosophila development
Syncytial blastoderm
What is the third dimension in the development of Drosophila, and when does this dimension form?
The proximal-distal axis, which forms during gastrulation
These genes set up the body axes
Maternal genes
Those genes which are required for subsequent development of Drosophila at later developmental stages
Zygotic genes
The four main classes of zygotic genes
Gap genes, Pair-rule genes, Segment polarity genes, and Homeotic/Selector genes
Selector genes depend on which sets of zygotic genes?
Gap genes, and Pair-rule genes
Three classes of maternal genes that define the antero-posterior axis
Those that affect anterior regions, posterior regions, and the terminal regions
T/F: Maternal genes establish differences in the antero-posterior axis after fertilization
F
Mutations that, when present in the mother, do not affect her but affects her progeny
Maternal-effect mutations
T/F: Bicoid gene expression affect nanos gene expression
F, they work independently
Mutations in what maternal gene will lead to the absence of the acron and telson?
Torso
From what germ layer does the ovary of the mother derive from?
Mesoderm
Where in the unfertilized egg is bicoid mRNA localized?
Anterior end
When is bicoid mRNA translated?
At fertilization
If a normal fertilized egg has parts A, B, C, D, and E (from anterior to posterior), and a mutant bicoid fertilized egg was injected with external bicoid at site C. What will be the arrangement of parts in the injected bicoid mutant? Assume that a larva can only have 5 parts in its antero-posterior axis.
C, B, A, B, C
What is the maternal gene that encodes for a protein that relocates bicoid mRNA to the anterior end of an egg?
Exuperantia
What is the half-life of the bicoid protein?
30 minutes
T/F: For proper patterning of the antero-posterior axis, a functioning bicoid gradient is enough.
F, both ends must be specified
This group of maternal genes control the posterior development of the Drosophila body plan
Posterior group genes
The development of what structure is impeded by mutations in posterior group genes?
Abdomen
This maternal gene product localizes nanos mRNA to the posterior end of the fertilized egg
Oskar
This maternal gene product specifies the posterior germ plasm, which eventually gives rise to the germ cells of Drosophila
Oskar
Nanos is present in the unfertilized egg as what?
mRNA
What maternal gene product/s makes a morphogen gradient with its highest level at the posterior end?
Nanos and Caudal
The expression of what (specify source) is inhibited by nanos protein?
Maternal hunchback
What causes the translation of zygotic hunchback?
Bicoid
Nanos prevents the expression of maternal hunchback by binding to the complex of? (2)
Maternal hunchback mRNA and Pumilio
If a maternal hunchback mutant were to be created, but somehow nanos expression was disturbed in the process, will the egg develop to be normal still? Why?
Yes, because the only function of nanos is to suppress maternal hunchback expression
Where is caudal mRNA initially found?
Uniformly distributed in the egg
What inhibits caudal protein expression?
Bicoid
Does the development of the two terminal regions utilize separate pathways?
No, both use the same pathway
What is the receptor protein that is important in specifying the terminal regions of the egg?
Torso